1. Field of the Invention
The present invention relates to an active object detection sensor that projects a detection beam and that detects an object based on a reception signal that depends on the beam reflected by the object.
2. Description of Related Art
To date, an active object detection sensor has been known which projects a detection beam such as an infrared beam from a projector onto a detection area, causes a receiver to receive the beam reflected by the object to generate a reception signal, and detects the object such as a human body when the reception signal has a level that exceeds a setting level.
On the other hand, in an automatic door having a touch switch, the door opens only by the touch switch being touched. Instead of such a touch switch being provided, a guide mark that indicates, for example, “Please touch with hand” is attached to a door in some cases (Japanese Patent No. 5150810). When a person who would like to open the door, moves his/her hand close to the guide mark, an active object detection sensor that forms a touch detection area immediately surrounding the guide mark, detects the hand in the touch detection area.
The touch detection area is adjusted by an installation worker after the automatic door, and an automatic door sensor device that includes the active object detection sensor which forms a detection area, are installed. For example, while the installation worker is moving an object, such as a reflector plate in positions estimated as a boundary of the touch detection area, the installation worker monitors a reaction of the active object detection sensor, that is, a result as to whether or not the beam reflected by the reflector plate are detected. Thus, the installation worker is allowed to recognize the boundary of the invisible touch detection area. Then, the installation worker who recognizes the boundary of the touch detection area, adjusts an orientation of the active object detection sensor such that the touch detection area is adjusted so as to be in a position proper for the automatic door, that is, in a position immediately surrounding the guide mark.
In this adjustment, the active object detection sensor outputs a result representing “detected” when the reflector plate is positioned in the touch detection area, whereas the active object detection sensor outputs a result representing “not detected” when the reflector plate is positioned outside the touch detection area. That is, the adjustment of the touch detection area is performed based on two values representing “detected” and “not detected”, whereby a circumferential boundary of the touch detection area is approximately identified.
On the other hand, a device is known which allows an operator to recognize an amount of the beam received by an infrared sensor in an optical axis adjustment between a light projecting unit and a light receiving unit in an intruder detection device (JP Laid-open Patent Publication No. H06-68366). This device allows the operator to easily recognize an amount of light received by the infrared sensor, by, for example, an LED being caused to blink at a frequency corresponding to the amount of light received by the infrared sensor. Thus, the operator may adjust an optical axis such that an amount of light received by the infrared sensor becomes maximum.